(prokaryotes) viruses attack eukaryotic cells.

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Viruses
Contoh Gambar Virus Cacar :
Gambar strukturnya :
Ciri-ciri :
1.
2.
3.
4.
5.
6.
7.
Bersifat aseluler
Hanya memiliki salah satu asam nukleat (RNA atau
DNA)
Berupa hablur (kristal)
Bentuk virus
: oval, silinder, polihedral dan komplek
( ct. bakteriofag)
Ukuran :
Reproduksi : Litic dan lisogenik
Peranan virus bagi kehidupan
a. Virus yang merugikan (manusia,tumbuhan dan
hewan).
b. Virus yang menguntungkan
SEJARAH VIRUS
Ilmu tentang Virus disebut Virologi.
Virus (bahasa latin) virion yang berarti racun
Virus adalah organisme aselular (bukan sel) yang tidak memiliki
organel-organel.
Sejarah Penemuan Virus
1. Edward Jenner (1749-1823) adalah ilmuwan pertama
yang berhasil menemukan vaksin mencegah penyakit
cacar (variola). Penyakit cacar (variola) disebabkan
virus.
2. Louis Paster adalah ilmuwan Perancis yang berhasil
menemukan pusat infeksi penyakit terdapat pada otak
dan medula spinalis. Selain itu, ia juga mampu
memindahkan infeksi tsb ke hewan percobaan di dalam
laboratorium.
3. Adolf Meyer (jerman), 1883 adalah ahli mikrobiolog
bahwa :
Daun tembakau berbintik-bintik kuning  organisme
lebih kecil dari bakteri.
Buktinya : menyemprotkan getah tanaman yang sakit
ke tanaman yang sehat ternyata tertular.
4. Dimitri Ivanowsky (Rusia), 1893. ahli botani 
Tanaman tembakau terkena penyakit mosaik.
Kemudian menyaring melalui pori-pori yg sgt halus
ternyata masih mampu menginfeksi daun tembakau.
5. M.W. Beijerinck, 1897.( Belanda) penyakit tembakau
mengandung jasad hidup yang disebut virus
6. Wendell Stanley (Amerika Serikat), 1935.
7. Loffler dan Forsch (1897) ilmuwan dari
Jerman
Virus yang menyerang hewan yakni penyakit
kuku dan mulut pada hewan ternak.
8. Reed (1900)
Virus menyebabkan penyakit demam berdarah
pada manusia. Penyakit disebabkan nyamuk
Aedes aegypti.
9. Laidraw dan Stuart Harris (1933-1936)
Menemukan virus influenza.
10.Jonas Salk (1953) menemukan vaksin
pencegah penyakit polio.
Viruses The Boundary of Life
parasites responsible for causing many
diseases in living things (herpes and HIV in
humans, for example).
Viruses are found everywhere.
Viruses consist of a core of nucleic acid,
either DNA or RNA, and a protective
coat of protein molecules and
sometimes lipids.
In isolation, viruses and
bacteriophages show none of the
expected signs of life. They do not
respond to stimuli, they do not grow,
they do not do any of the things we
normally associate with life.
Strictly speaking, they should not be
considered "living" organisms at all.
However, they are more complex than
a lifeless collection of macromolecules
and they do show one of the most
important signs of life: the ability to
reproduce at a fantastic rate
but only in a host cell.
Bacteriophages attack bacteria
(prokaryotes)
viruses attack eukaryotic cells.
Viruses and bacteriophages invade cells
and use the host cell's machinery to
synthesize more of their own
macromolecules.
Once inside the host the bacteriophage or
virus will either go into a Lytic Cycle -
destroying the host cell during
reproduction.
or
It will go into a Lysogenic Cycle - a
parasitic type of partnership with
the cell
The Lytic Cycle
The Lysogenic Cycle
A provirus is a DNA virus that has been inserted into a host
cell chromosome.
A retrovirus injects the enzyme, reverse transcriptase into the cell
to copy viral RNA into DNA.
HIV is a retrovirus injecting the enzyme, reverse
transcriptase into the cell to copy viral RNA into DNA.
Viruses are host specific – a protein on the surface of the virus
has a shape that matches a molecule in the plasma membrane
of its host, allowing the virus to lock onto the host cell.
HIV doesn’t target just any cell, it goes right for the cells that
want to kill it. “Helper" T cells are HIV's primary target. These
cells help direct the immune system's response to various
pathogens.
HIV undermines the body's ability to
protect against disease by depleting T
cells thus destroying the immune system.
The virus can infect 10 billion cells a day,
yet only 1.8 billion can be replaced daily.
After many years of a constant battle, the body
has insufficient numbers of T-Cells to mount an
immune response against infections. At the point
when the body is unable to fight off infections, a
person is said to have the disease AIDS.
It is not the virus or the disease that ultimately
kills a person; it is the inability to fight off
something as minor as the common cold.
VIRUS YANG
MENGUNTUNGKAN
1). Virus dapat dimanfaatkan dalam bidang rekayasa
genetika (vektor mutasi gen) maupun penelitian di
bidang kedokteran.
2). Virus yang digunakan untuk memproduksi interferon
berfungsi untuk mencegah replikasi virus di dalam sel
hospes. Interferon merupakan protein kecil yang
dihasilkan oleh sel normal sebagai respon terhadap
infeksi virus.
3). Virus digunakan untuk pembuatan vaksin. Vaksin
adalah mikroorganisme patogen yang telah
dilemahkan sehingga sifat-sifat patogenitas penyebab
penyakitnya hilang, tetapi sifat-sifatnya antigenitas
penimbul antibodi tetap.
TUGAS
Buatlah ringkasan dari materi ini
Tugas dikumpulkan melalui email
[email protected] (paling
lambat 9 April 2015)
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